Axial flow rotary feeder for cellulose digester



NOV- 19, 1958 R. L''BUcHBr-:RGER ETAL 3,411,986

AXIAL FLOW ROTARY FEEDER FOR CELLULOSE DGESTEH Filed Aug. 4, 1965 5Sheets-Sheet l [uw 2%/ ATTORNEYS l M l I 291/ Nov. 19, 1968 R. l..BUCHBERGER ETAL 3,411,986

AXIAL FLOW ROTARY FEEDER FOR CELLULOSE DIGESTER Filed Aug. i., 1965 3Sheets-Sheet 2 46 mw ATTORNEYS Nov. 19, 1968 R. L. BUCHBERGER ETAL AXALFLOW ROTARY FEEDER FOR CELLULOSE DIGESTER Filed Aug. 4, 1965 5Sheets-Sheet 5 Q M ATTORNEYS United States Patent 3,411,986 AXIAL FLOWROTARY FEEDER FOR CELLULOSE DIGESTER Ronald L. Buchberger and Arnold J.Roerig, Beloit, Wis.,

assignors to Beloit Corporation, Beloit, Wis., a corporation ofWisconsin Filed Aug. 4, 1965, Ser. No. 477,242 4 Claims. (Cl. 162-246)ABSTRACT OF THE DISCLOSURE Apparatus for feeding cellulosic material toa continuous pulping digester. The apparatus is a rotary feeder valvehaving -a frusto-conically shaped bore with at least two pairs of inletsand outlets therein and a complementarily shaped rotor in the bore withpassages in the rotor. The passages are arranged to interconnect rst oneof the said pairs of inlets and outlets -an'd then the other pair uponrotation of the rotor and screens are placed in either the rotor or theoutlets in the bore for collecting chips in the passages.

This invention relates generally to pulp and paper-making apparatus `andmore particularly to apparatus for transferring and feeding wood chipsduring a continuous pulping process.

Advances have been made in the development of continuous pulpingprocesses `and there are now a number of soundly developed systems forcontinuous pulping, particularly of the chemical and semi-chemicaltypes. Continuous pulping can afford many advantages over a batchoperation, among which are reduced time requirements, a more uniformproduct, utilization of better control methods, greater exibility andthe ability to use lower liquor ratios.

Continuous pulping processes are often complicated, however, and havepresented problems of mechanical design. For example, in some operationssuch as in feeding wood chips to the digesters or in transferring thewood ychips from one digester to another the chips may desirably befirst carried in one fluid medium such as a first liquor and thentransferred to another liuid medium such as a second liquor which mightbe at a different pressure, temperature, etc., than the lirst liquor.

The present invention is addressed to such problems and provides meansnot only for effecting such transfer but for accomplishing the transfercontinuously las required in feeding wood chips in a continuous pulpingprocess.

The feeding or transfer apparatus of the present invention is simple indesign, relatively inexpensive in manufacture, provides a high transferor feeding capacity, is easy to operate, can be controlledautomatically, is rugged in construction and can serve a long, usefullife.

It is, therefore, an object of the present invention to provide meansfor transferring wood chips from a first liquor to a second liquor, thetwo liquors having different conditions of pressure or temperature orthe like.

Another object of the invention is to provide a digesting system for acontinuous pulping process including means for continuously deliveringwood chips to the digester for processing.

Another object `of the invention is to provide `a rotary feeder for adigester system incorporating a stationary stator and :a rotatable rotorand including means for reducing wear between the stator and the rotor.

A further object of the invention is to provide, in a vertical feederhaving la rotor rotatable within the bore of a stationary stator, apressurized chamber within the bore to counterbalance the weight of thestator to reduce wear.

3,41 1,986 Patented Nov. 19, 1968 "ice Yet another object of theinvention is to provide a feeder for 'a digester system in a continuouspulping process whereby wood chips are continuously transferred from `afirst liquor to `a second liquor for delivery to a digester, and inwhich only one moving part is required in the feeder.

Still another object of the invention is to provide a feeder or transfermechanism which is simple in design, relatively inexpensive inmanufacture, provides a high transfer capacity, is easy to operate, isrugged in construction, `and can serve a long, useful life.

Many other features, advantages and additional objects of the presentinvention will become manifest t0 those versed in the :art upon makingreference to the detailed description which follows and the accompanyingsheets lof drawings, in which preferred structural embodimentsincorporating the principles of the present invention are shown by wayof illustrative example only.

In the drawings FIGURE 1 is a schematic plumbing diagram of a continuousdigesting system incorporating the principles of the present invention;

FIGURE 2 is a side elevational view of a transfer or feeder unitconstructed in accordance with the principles of the present invention;

FIGURE 3 is a top plan view of the feeder unit of FIGURE 2;

FIGURE 4 is a sectional side view of the feeder unit taken along linesIV-IV of FIGURE 3;

FIGURE 5 is a horizontal sectional view of the feeder unit taken alonglines V-V of FIGURE 4; and

FIGURE 6 is a fragmentary vertical sectional view of the feederillustrating another embodiment of .a screening rmeans thereof.

As shown in the drawings Although the principles of the presentinvention are applicable in any system wherein solids are to betransferred from one fluid medium to another; a particularly usefulapplication is made to a pulping process in the Imanufacture of stockfor making paper products wherein wood chips are treated mechanicallyand/or chemically at a plurality of treatment stations or zones and maybe transferred from one treatment zone to another in one or more liquormediums, as will be understood by those skilled in the art.

The present invention is also particularly useful where the transfer ofthe solids is essentially a continuous process. For example, generallyin a pulping process the wood chips are subjected to ycertain treatmentbefore entering the digesters. In a batch operation, the chips are movedperiodically lfrom one treatment station or zone to another, and thendelivered to the digester or digesters in a slug or batch. As notedhereinabove, a batch operation is not generally as desirable as acontinuous process wherein the chips are continuously moved through thevarious treatment zones and into and through the digesters.

A continuous pulping lprocess, however, raises certain problems, not theleast of which involves the continuous transfer of the chips from onefluid medium to another through the various treatment zones and into thedigesters.

The present invention provides improved means for effecting suchtransfer and for continuously moving the chips through the varioustreatment zones and into the digesters. Y

Referring to FIGURE 1, a typical digester is indicated generally atreference numeral 10. Usually the digester receives the chips after theyhave been worked on in other treatment zones.

For example, in some pulping processes the chips are delivered from achipper or a grinder ina first liquor medium to a first treatment zone.The particular liquor utilized is generally necessary for the propertreatment of the chips and after this phase of the process is completedthe chips may be moved to a second treatment zone. The second treatmentmay require a second liquor, which may be chemically dilferent from thefirst liquor or may differ only in temperature or pressure. In anyevent, it may not be the same liquor or lmay not be maintained under thesame conditions as the first liquor, and therefore the chips aretransferred from the first to the second liquor. In so doing the twotreatment zones should re- -main isolated from one another so that ahigher pressure or temperature of the liquor of one will not be reducedto that of the other.

In FIGURE 1 it will be assumed that the treatment involved in thedigester requires a high pressure liquor and that the next precedingtreatment station utilizes a liquor similar to the liquor used in thedigester process, but maintained at a lower pressure. It will beunderstood, however, that the difference between the two liquors couldbe temperature rather than pressure, or temperature and Ipressure, orthe two liquors could differ chemically. However, for one or more ofthese reasons it is assumed that it is desirable to keep the two liquorsseparated, or at least substantially so.

Reference numeral 11 denotes a conduit for conveying a flow of lowpressure liquor having wood chips suspended therein from a treatmentzone which next precedes the digester 10 in a pulping process. Assumethat the digester 10 utilizes a high pressure liquor which is conveyedby a conduit 12 and which ows in the direction indicated from a sourcethereof. The wood chips being carried in the low pressure liquor inconduit 11 are to be transferred to the high pressure liquor iiowing inconduit 12, and `for that purpose the respective conduits are connectedto a feeder or transfer unit indicated generally at 13 which isconstructed in accordance with the principles Iof the present invention.

Reference numeral 14 denotes a conduit carrying the Vlow pressure liquorafter it has passed through the feeder unit 13 and after the wood chipshave been removed therefrom and transferred to the high pressure liquor.Reference numeral 16 denotes a conduit carrying the high pressure liquorafter it has passed through the feeder 13 and after the chips have beentransferred thereto, and this conduit is connected to the digester 10for feeding the digester with a supply of treated chips.

Referring to FIGURES 2 and 3, the feeder unit 13 is more particularlycharacterized as comprising a generally cylindrically shaped verticallyupstanding stator portion 17, a drive portion 18 at the lower end of thestator and having suitable drive means such as an electric motor 19,connected thereto, and a top portion 20 situated at the upper end of thestator and having mounted thereon a bearing assembly indicated generallyat reference numetal 21.

A plurality of conduit connectors extend from the stator 17 and areadapted for connection to the various conduits which receive and delivertheliquor and wood chips transferred to and from the feeder 13.

For example, in the illustrated embodiment of the feeder 13 fourconnectors indicated respectively at reference numerals 22a-22d areconnected in fixed assembly by suitable means such as a weldl connectionor the like to the upper portion of the body or stator 17 and are spacedcircumferentially 90 around the periphery of the stator. At the lowerend of the stator another group of four connectors indicated at 23a-23dare also mounted on the stator in vertical alignment with connectors22a-22d. Each 0f the connectors includes a ange 24 for connection to thevarious conduits 11, 12, 14 and 16 although it will be understood thatwhere two or more of the connectors are connected to a single conduitsuitable means such as a header `may be utilized in making theconnection.

Referring to FIGURES 4 and 5 it will be noted that all of the connectorsare in open communication with the interior of the body or statorportion 17 through a plurality of complementarily aligned openings asindicated at 25 formed in a longitudinal wall 26 of the stator 17.

Rotatably carried within the stator 17 is a generally cylindricallyshaped rotor 27 having formed therein a plurality of axially extendingpassages which in the embodiment illustrated are constructed as recessesformed in a peripheral wall 28 of the rotor 27. The passages are eightin number indicated respectively at reference characters 29g-2911 andare spaced circumferentially equi- -distantly around the periphery ofthe rotor. Each of the passages is separated from adjacent passages bymeans of a pair of diverging walls 30 and 31 which extend-radiallyoutwardly from a center or hub portion 32 of the rotor.

Also housed within the stator 17 is a tubular liner 33 Iwhich is shapedcomplementarily to an inner surface 34 of the stator wall 26 and theperipheral surface 28 of the rotor 27. The liner 33 also has formedtherein a plurality of complementarily aligned openings as at 36 toafford open communication of the connectors with the interior of thestator 17.

A pair of coaxial shafts 37 and 38 extend from opposite end walls 39 and40 of the rotor 27, shaft 37 extending upwardly into the top portion 20of the feeder and shaft 38 extending vertically ldownwardly into thedrive portion 18. Suitable packing members 41 and 42 are provided on therespective shafts 37 and 38 for pre'- venting excessive leakagetherepast. A pair of radial thrust bearings 43 and 44 are mountedrespectively in the top portion 20 and the drive portion 18 forjournalling shafts 37 and 38 and in order to rotate the rotor 27 a lowerend 46 of the shaft 28 is splined for driving connection with a gear 47which is in meshing engagement with a Aworm gear co-rotatably connectedto a drive shaft 48 driven by the motor 19 (FIGURE 2).

In order to explain the operation of the feeder 13 assume thatconnectors 221, and 22d are connected by suitable header means tocon-duit 11 which is, in turn, connected to the source of a first liquorand chips, and connectors 23h and 23d, which are spaced axially fromconnectors 22h and 22d, are connected =by suitable header means toconduit 14 for carrying away the first or low pressure liquor from thefeeder after the chips Ihave' been removed therefrom. Connectors 22a and22e are connected by conduit 12 to the second or high pressure liquor towhich the chips are to be transferred and connectors 23,l and 23c areconnected to the conduit 16 for delivering the second liquor and chipsto the digester 10. It will be appreciated, however, that connectors 22aand 22c could be connected to conduit 16 and connectors 23a and 23c toconduit 12 for reverse -ow of the second liquor through the feeder 13.

As the rotor 27 is turned by the drive mechanism each of the passages29-291l will sequentially interconnect in fluid communication firstconnectors 22d and 23d (likewise 22h and 23h) and then connectors 22aand 23a (likewise 22c and 23C). y

For example, in FIGURE 4 the passage 29g is situated so as tocommunicate connector 22d with connector 23d. The first liquor and chipsthereby flow from connector 22d into the passage 29g, wherein the chipsare retained bymeans of a screen 49 formed in the liner 33 across theopening of the connector 23d. Y

Upon continued rotation of the rotor 27 (approximately for theembodiment illustrated) the passage 29g with the chips collected thereinwill communicate connectors 22,a and 23a, whereupon the chips will behushed from the passage to be delivered with the second liquor to thedigester.

It will lbe appreciated that as a resultof the arrangement of thepassages 29g-29h, a quantity of chips are continuously collected in twoof the passages and are continuously flushed from two differentpassages, as a result of which the transfer of the chips from the firstto the second liquor and the delivery of the second liquor and chips tothe digester is a substantially continuous operation.

lt may be desirable for the screen means to be for-med directly on therotor 27 rather than in the liner 49 (which is effectively the body wall26). Referring to FIGURE 6, in an alternative arrangement a screenmember 49a shaped complementarily to the curvature of the liner 26 ismounted at the lower end of a typical passage 29 for collecting thechips in the passage. It will be appreciated that in this arrangement ascreen member 49a is required for each of the passages 29,72%, andfurthermore it will be appreciated that the second liquor must bebackflushed through the rotor to ush the chips therefrom. In FIGURE 4,for example, if a plurality of screen members 49a were -mountedrespectively at the lower end of each of the passages 29g-29h, theconduit 12 (FIGURE 1) would be connected to the connector 23 rather than22 and conduit 16 would be connected to connector 22a, whereby thesecond liquor would back ush the chips olf of the screen members 49.,1and out of the passages as the respective passages interconnectedconnectors 23a and ln or-der to provide a good sealing or substantiallyleakproof relation between the engaging faces of the rotor 27 and theliner 33, in the illustrated embodiment the wall 26 of the stator 17,the liner 33 and the peripheral wall 28 of the rotor 27 arefrusto-conically shaped and taper inwardly at the lower end thereof. Agap or space 50 is provided between the top end wall 39 of the rotor 27and a radial face or end plate 51 of the top portion 20. A relativelylarger space or chamber 52 is provided between the lower end wall of therotor 27 and a radial end plate 53 of the drive portion 18. As aconsequence thereof the rotor 27 is movable axially within the stator 17Iwithin the limits defined by the end plates 51 and 53.

ln or-der to counterbalance the weight of the rotor 27 and the axialforces acting on the rotor as a result of the flow of liquortherethrough, and also to reduce wear between the engaging faces of therotor 27 and the liner 33, a conduit 54 is connected at one end 56thereof to the lower chamber 52, and at the other end thereof to asuitable source of pressurized uid. A pressure regulator valve 57 ismounted in conduit 54 in order to regulate the pressure of chamber 52and to thereby control the counterbalancing effect on the rotor 27.

Any pressurized uid may be utilized for this purpose. If steam isavailable an additional conduit 58 may also be connected to chamber 52for removing condensate from the chamber and a steam trap or condensateValve 59 may preferably be mounted in the conduit 58 as will beunderstood by those skilled in the art.

In order to accommodate axial thrust of the rotor 27 as a result of thepressurization of chamber 52, an axial thrust bearing 60 is mounted atthe upper end of shaft 37 and is restricted in upward movement thereofby a collar 61 and the axial thrust bearing 60, a handle 66 is mountedmay be adjusted vertically by means of a threaded stud 62 connected tothe collar 61 and received in a complementarily threaded bore 63 formedin a cover 64 of the bearing assembly 21. In order to facilitaterotation of the stud 62 and consequently vertical adjustment of thecollar 61 and the axial thrust bearing 60, a handle 66 is mounted at theupper end of the stud 62.

As a result ofthe axial adjustability of the thrust bearing 60, thelower chamber 52 may be pressurized to a relatively high pressure butthe rotor 27 will be limited in axial movement to provide for minimumwear between the engaging faces of the rotor 27 and the liner 33 whilealso maintaining a substantially leak-proof relationship therebetween.

With respect to radial thrust forces acting on the rotor 27 it will benoted that as a result of the diametrically opposite arrangement of theconnectors 22h and 22d, both of which yare connected to the firstliquor, the diametrically opposite arrangement of the connectors 22,Land 22C, which are spaced circumferentially with respect to connectors22h and 22d and both of which are connected to the second liquor, andthe diametrically opposite arrangement of the corresponding connectors23a-233, the radial thrust forces acting on the rotor 27 are completelybalanced, regardless of the angular disposition of the rotor duringrotation thereof.

Although in the embodiment illustrated the lower connectors 23a-23d arein vertical alignment with the connectors 22a-22d, it will beappreciated that the upper and lower connectors may be lsomewhatcircumferentially offset with respect to one another while maintaining a90 circumferential spacing between the connectors 22B-22d and `betweenconnectors 23a-23d to maintain a balanced radial thrust condition on therotor 27.Such arrangement, of course, would necessitate a correspondinghelical construction of the passages 29-291l in the event that thedegree of offset between the axially spaced upper and lower connectorsrequired such modification.

Although these and other minor modifications might be suggested by thoseversed in the art, it should be understood that we wish to embody withinthe scope of the patent warranted hereon all such modifications asreasonably come Within the scope of our contribution to the art.

We claim as our invention:

1. In a digester system for digesting wood chips,

a rotary feeder for liquor and chips comprising a stator having meansforming a vertically extending frusto-conically shaped bore therein,means forming at least two pairs of openings in said stator each ofwhich pairs comprises an inlet and an outlet,

a complementarily shaped rotor rotatably carried in said bore and havingmeans forming a plurality of passages therein,

said passages each being arranged to successively interconnect lirst oneof said pairs of said openings and then another of said pairs uponrotation of said rotor,

screen means between said one pair of said openings for collecting chipsin said passages as each passage interconnects said one pair of saidopenings,

means for rotating said rotor in said stator,

bearing means for journalling Isaid 'rotor in said stator and foraccommodating axial thrust, and

means for moving said bearing means axially to provide axial movement ofsaid rotor in said stator.

2. In a digester system for digesting wood chips,

a rotary yfeeder for liquor and chips comprising a stator having meansforming a vertically extending frustoconically shaped bore therein withthe larger diameter end of said bore situated at the upper end thereof,

means forming at least two pairs of openings in said stator each ofwhich pairs comprises an inlet and an outlet,

a complementarily shaped rotor rotatably carried in said bore and havingmeans `forming a plurality of passages therein,

said passages each being arranged to successively interconnect rst oneof said pairs of said openings and then another of said pairs uponrotation of said rotor,

the length of said rotor being less than the length of said bore toprovide a chamber therebetween at the lower end thereof,

screen means between said one pair of said openings for collecting chipsin said passages as each passage interconnects said one pair of saidopenings,

means for rotating said rotor in said stator, and

" conduit means for introducing a pressurized uid into said chamber tocounterbalance the effective weight of said rotor and to reduce wearbetween said rotor and the wall of said bore.

3. In a digester system for digesting wood chips,

a rotary feeder for liquor and chips comprising a stator having meansforming a vertically extending frustoconically shaped bore therein withthe larger diameter end of said bore situated at the :upper end thereofmeans forming at least two pairs of openings in said stator each ofwhich pairs comprises an inlet and an outlet,

' a complementarily shaped rotor rotatably carried in said bore andhaving means forming a plurality of passages therein,

said passages each being arranged to successively interconect rst one ofsaid pairs of said openings and then another of said pairs upon rotationof said rotor, the length of said rotor being less than the length ofsaid bore to provide a chamber therebetween at the lower end thereof,screen means between said one pair of said openings for collecting chipsin said passages as each passage interconects said one pair of saidopenings, means for rotating said rotor in said stator, conduit meansfor introducing a pressurized uid into said chamber to counterbalancethe effective weight of said rotor and to reduce wear between said rotorand the Wall of said bore, and valve means in said conduit means forcontrolling the pressure of the iluid in said chamber. 4. In a digestersystem for digesting wood chips, a rotary feeder for liquor and chipscomprising a stator having means forming a vertically extendingfrustoconically shaped bore therein,

means forming at least two pairs of openings in said stator each ofwhich pairs comprises an inlet and an outlet,

a complementarily shaped rotor rotatably carried in said bore and havingmeans forming a plurality of passages therein.

said passages each being arranged to successively interconnect first oneof said pairs of said openings and then another of said pairs uponrotation of said rotor, the length of said rotor being less than thelength of said bore to provide a chamber therebetween at one end of thebore,

screen means between said one pair of said openings for collecting chipsin said passages as each passage interconects said one pair of saidopenings,

means for rotating said rotor in said stator,

axially adjustable bearing means for journalling said rotor in saidstator and for accommodating axial thrust,

1 conduit means for introducing a pressurized uid into said chamber, and

valve means in said conduit means for controlling the pressure of thefluid in said chamber in order to control the axial thrust on saidbearing means.

References Cited UNITED STATES PATENTS a S. LEON BASHORE, PrimaryExaminer.

